During an intramuscular injection, medication is generally delivered directly into a muscle, such as a thigh or buttocks. Examples of medications administered intramuscularly, include codeine, metoclopramide, and epinephrine. One of the advantages of injecting medication intramuscularly, is that intramuscular injections are generally absorbed into the muscle fairly quickly, in comparison to other types of injections, such as subcutaneous injections, which have a more gradual absorption rate. Intramuscular injections into body locations, such as the buttocks, and/or thigh, are generally known to reach the bloodstream fairly quickly, due to the large amount of muscular tissue and corresponding blood supply.
The ability to perform an intramuscular injection with accuracy and speed is vital. While most intramuscular injections are administered to patients by trained medical professionals, such as doctors, nurses or physician assistants, self-administered intramuscular injections are becoming more common for patients who require these injections either routinely or immediately. In such cases, the aforementioned medical professionals are typically unavailable. Immediate administration is particularly important when treating illnesses such as Anaphylaxis, in which a serious allergic reaction is rapid in onset, and may cause death if not treated with speed and accuracy.
In general, anaphylaxis may be treated by administration of epinephrine, as well as other medications. Patients are typically prescribed an auto-injector of epinephrine, such as an Epipen® to treat sudden anaphylaxis. Some of the challenges when self-administering epinephrine is that it is not only critical that the medication is administered in a timely manner, it is also important that the dosage is effectively administered into the muscle for rapid distribution. By design, auto-injectors are generally easy to use and intended for self-administration by patients, or untrained individuals. Most auto-injectors are spring-loaded syringes configured to hold a pre-determined dosage of medication. A user suffering from anaphylaxis has a limited amount of time to make a proper injection. Accordingly, failure to inject medication during illness, within a certain time frame, can be fatal.
Conventional injection devices, such as the Epipen®, are usually prescribed to a patient based on the patient's size. Some auto-injectors provide that the needle size can be varied. Providing the proper needle size or auto-injector size is critical, as the intramuscular injection depth varies based on several factors, including the size of patient, and the density of tissue layers between the outer layer and muscle. For example, the muscle depth of a large 300 pound person with thick layers of adipose is greater than that of a thin 50 pound small child.
While, the injection depth of the auto-injector can be adjustable or fixed, it is vitally important that the injection depth is accurate. For example, with regard to Epipen® having a needle length of 14.3 mm, the anterolateral thigh (Vastuslateralis) is the appropriate location for injection. Other known intramuscular injection guidelines for vaccination provide that infants under the age of 18 months should have a needle length generally between ⅝″-1″ (16 mm-25 mm) and injections should be made into the Vastuslateralis muscle. The guidelines further provide that children older than 18 months and under the age of 18 should have needle lengths between ⅞″-1¼″(22 mm-32 mm) and injections should be made into the Deltoid muscle, Ventrogluteal site, Dorsogluteal site or Vastuslateralis muscle. Guidelines further provide that adults should have a needle length between 1″-1½″ (25 mm-38 mm) and injections should be made into the Deltoid muscle, Ventroglutealsite, Dorsogluteal site (however not in obese adults) or Vastuslateralis. While these guidelines are instructive, determining the most effective location and needle length may vary based on the actual size of the human being.
Auto-injectors may be activated by pressing a button located on the auto-injector or other firing mechanism, such that the syringe needle is automatically exerted. Most auto-injectors are spring-loaded syringes configured to hold a pre-determined dosage of medication. The medication is then delivered by the auto-injector needle through the outer skin into the muscle with an impactful force. Once the injection is completed, some auto-injectors provide a visual indication to confirm that the full dose has been delivered. While the visual indication feature is helpful, most auto-injectors do not indicate whether the device actually released the medication into the muscle, or accidentally into an organ and/or tissue proximate to the muscle. Failure to contact the muscle on injection can diminish the effectiveness of the dosage. Accordingly, it is important for the user to be able to accurately locate the muscle. It is further important to properly size the auto-injector, such that the needle has the correct length to achieve the proper injection depth, and thus provide effective administration. One existing problem, is that health care professionals do not have a device or method to accurately measure the distance from the outer skin layer, to the muscle upon injection of an auto-injector.
The foregoing objects and advantages of the invention are illustrative of those that can be achieved by the various exemplary embodiments and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of the various exemplary embodiments will be apparent from the description herein or can be learned from practicing the various exemplary embodiments, both as embodied herein or as modified in view of any variation that may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel methods, arrangements, combinations, and improvements herein shown and described in various exemplary embodiments.